Sedentary lifestyle increases the likelihood of development of insulin resistance. It has been estimated that each 500 kcal/week increment in physical activity related energy expenditure, reduces the lifetime risk of type 2 diabetes by 9%. A different study found that vigorous exercise at least once a week reduced the risk of type 2 diabetes in women by 33%.

These unclassified forms are extremely rare:

- Hyperalphalipoproteinemia

- Polygenic hypercholesterolemia

Testing the general population under the age of 40 without symptoms is of unclear benefit.

Familial hypertriglyceridemia is an autosomal dominant condition occurring in approximately 1% of the population.

This form is due to high triglyceride level. Other lipoprotein levels are normal or increased a little.

Treatment include diet control, fibrates and niacins. Statins are not better than fibrates when lowering triglyceride levels.

Protease inhibitors found in HIV drugs are linked to insulin resistance.

Since hyperinsulinemia and obesity are so closely linked it is hard to determine whether hyperinsulinemia causes obesity or obesity causes hyperinsulinemia, or both.

Obesity is characterized by an excess of adipose tissue – insulin increases the synthesis of fatty acids from glucose, facilitates the entry of glucose into adipocytes and inhibits breakdown of fat in adipocytes.

On the other hand, adipose tissue is known to secrete various metabolites, hormones and cytokines that may play a role in causing hyperinsulinemia. Specifically cytokines secreted by adipose tissue directly affect the insulin signalling cascade, and thus insulin secretion. Adiponectins are cytokines that are inversely related to percent body fat; that is people with a low body fat will have higher concentrations of adiponectins where as people with high body fat will have lower concentrations of adiponectins. Weyer "et al." (2011) reported that hyperinsulinemia is strongly associated with low adiponectin concentrations in obese people, though whether low adiponectin has a causal role in hyperinsulinemia remains to be established.

- May lead to hypoglycemia or diabetes

- Increased risk of PCOS

- Increased synthesis of VLDL (hypertriglyceridemia)

- Hypertension (insulin increases sodium retention by the renal tubules)

- Coronary Artery Disease (increased insulin damages endothelial cells)

- Increased risk of cardiovascular disease

- Weight gain and lethargy (possibly connected to an underactive thyroid)

Metabolic syndrome affects 60% of the U.S. population older than age 50. With respect to that demographic, the percentage of women having the syndrome is higher than that of men. The age dependency of the syndrome's prevalence is seen in most populations around the world.

Screening among family members of people with known FH is cost-effective. Other strategies such as universal screening at the age of 16 were suggested in 2001. The latter approach may however be less cost-effective in the short term. Screening at an age lower than 16 was thought likely to lead to an unacceptably high rate of false positives.

A 2007 meta-analysis found that "the proposed strategy of screening children and parents for familial hypercholesterolaemia could have considerable impact in preventing the medical consequences of this disorder in two generations simultaneously." "The use of total cholesterol alone may best discriminate between people with and without FH between the ages of 1 to 9 years."

Screening of toddlers has been suggested, and results of a trial on 10,000 one-year-olds were published in 2016. Work was needed to find whether screening was cost-effective, and acceptable to families.

Physical inactivity is a predictor of CVD events and related mortality. Many components of metabolic syndrome are associated with a sedentary lifestyle, including increased adipose tissue (predominantly central); reduced HDL cholesterol; and a trend toward increased triglycerides, blood pressure, and glucose in the genetically susceptible. Compared with individuals who watched television or videos or used their computers for less than one hour daily, those who carried out these behaviors for greater than four hours daily have a twofold increased risk of metabolic syndrome.

The American College of Endocrinology (ACE) and the American Association of Clinical Endocrinologists (AACE) have developed "lifestyle intervention" guidelines for preventing the onset of type 2 diabetes:

- Healthy meals (a diet with no saturated and trans fats, sugars, and refined carbohydrates, as well as limited the intake of sodium and total calories)

- Physical exercise (30–45 minutes of cardio vascular exercise per day, five days a week)

- Reducing weight by as little as 5–10 percent may have a significant impact on overall health

Possible causes include:

- Neoplasm

- Pancreatic cancer

- Polycystic ovary syndrome (PCOS)

- Trans fats

Dyslipidemia is an abnormal amount of lipids (e.g. triglycerides, cholesterol and/or fat phospholipids) in the blood. In developed countries, most dyslipidemias are hyperlipidemias; that is, an elevation of lipids in the blood. This is often due to diet and lifestyle. Prolonged elevation of insulin levels can also lead to dyslipidemia. Likewise, increased levels of O-GlcNAc transferase (OGT) may cause dyslipidemia.

The progression to type 2 diabetes mellitus is not inevitable for those with prediabetes. The progression into diabetes mellitus from prediabetes is approximately 25% over three to five years.

There are numerous theories as to the exact cause and mechanism in Type 2 Diabetes. Central obesity is known to predispose individuals for insulin resistance. Abdominal fat is especially active hormonally, secreting a group of hormones called adipokines that may possibly impair glucose tolerance. But adiponectin which is found in lower concentration in obese and diabetic individuals has shown to be beneficial and protective in Type 2 diabetes mellitus.

Insulin resistance is a major feature of Diabetes Mellitus Type 2 (T2DM), and central obesity is correlated with both insulin resistance and T2DM itself. Increased adiposity (obesity) raises serum resistin levels, which in turn directly correlate to insulin resistance. Studies have also confirmed a direct correlation between resistin levels and T2DM. And it is waistline adipose tissue (central obesity) which seems to be the foremost type of fat deposits contributing to rising levels of serum resistin. Conversely, serum resistin levels have been found to "decline" with decreased adiposity following medical treatment.

Developing asthma due to abdominal obesity is also a main concern. As a result of breathing at low lung volume, the muscles are tighter and the airway is narrower. It is commonly seen that people who are obese breathe quickly and often, while inhaling small volumes of air. People with obesity are also more likely to be hospitalized for asthma. A study has stated that 75% of patients treated for asthma in the emergency room were either overweight or obese.

Familial hypercholesterolemia (FH) is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein (LDL, "bad cholesterol"), in the blood and early cardiovascular disease. Since individuals with FH underlying body biochemistry is slightly different, their high cholesterol levels are less responsive to the kinds of cholesterol control methods which are usually more effective in people without FH (such as dietary modification and statin tablets). Nevertheless, treatment (including higher statin doses) is usually effective.

FH is classified as a type 2 familial dyslipidemia. There are five types of familial dyslipidemia (not including subtypes), and each are classified from both the altered lipid profile and by the genetic abnormality. For example, high LDL (often due to LDL receptor defect) is type 2. Others include defects in chylomicron metabolism, triglyceride metabolism, and metabolism of other cholesterol-containing particles, such as VLDL and IDL.

About 1 in 300 to 500 people have mutations in the "LDLR" gene that encodes the LDL receptor protein, which normally removes LDL from the circulation, or apolipoprotein B (ApoB), which is the part of LDL that binds with the receptor; mutations in other genes are rare. People who have one abnormal copy (are heterozygous) of the "LDLR" gene may develop cardiovascular disease prematurely at the age of 30 to 40. Having two abnormal copies (being "homozygous") may cause severe cardiovascular disease in childhood. Heterozygous FH is a common genetic disorder, inherited in an autosomal dominant pattern, occurring in 1:500 people in most countries; homozygous FH is much rarer, occurring in 1 in a million births.

Heterozygous FH is normally treated with statins, bile acid sequestrants, or other lipid lowering agents that lower cholesterol levels. New cases are generally offered genetic counseling. Homozygous FH often does not respond to medical therapy and may require other treatments, including LDL apheresis (removal of LDL in a method similar to dialysis) and occasionally liver transplantation.

Vitamin E supplements have shown to help children with the deficiency.

In the setting of critical illness, low cholesterol levels are predictive of clinical deterioration, and are correlated with altered cytokine levels.

In humans with genetic loss-of-function variants in one copy of the "ANGPTL3" gene, the serum LDL-C levels are reduced. In those with loss-of-function variants in both copies of "ANGPTL3", low LDL-C, low HDL-C, and low triglycerides are seen ("familial combined hypolipidemia").

Hooft disease is a rare condition evidenced by low blood lipid level, red rash and mental and physical retardation.

The relation between dietary fat and atherosclerosis is controversial. Writing in "Science", Gary Taubes detailed that political considerations played into the recommendations of government bodies. The USDA, in its food pyramid, promotes a diet of about 64% carbohydrates from total calories. The American Heart Association, the American Diabetes Association and the National Cholesterol Education Program make similar recommendations. In contrast, Prof Walter Willett (Harvard School of Public Health, PI of the second Nurses' Health Study) recommends much higher levels of fat, especially of monounsaturated and polyunsaturated fat. These differing views reach a consensus, though, against consumption of trans fats.

The role of dietary oxidized fats/lipid peroxidation (rancid fats) in humans is not clear.

Laboratory animals fed rancid fats develop atherosclerosis. Rats fed DHA-containing oils experienced marked disruptions to their antioxidant systems, and accumulated significant amounts of phospholipid hydroperoxide in their blood, livers and kidneys.

Rabbits fed atherogenic diets containing various oils were found to undergo the greatest amount of oxidative susceptibility of LDL via polyunsaturated oils. In another study, rabbits fed heated soybean oil "grossly induced atherosclerosis and marked liver damage were histologically and clinically demonstrated." However, Fred Kummerow claims that it is not dietary cholesterol, but oxysterols, or oxidized cholesterols, from fried foods and smoking, that are the culprit.

Rancid fats and oils taste very bad even in small amounts, so people avoid eating them.

It is very difficult to measure or estimate the actual human consumption of these substances. Highly unsaturated omega-3 rich oils such as fish oil are being sold in pill form so that the taste of oxidized or rancid fat is not apparent. The health food industry's dietary supplements are self regulated and outside of FDA regulations. To properly protect unsaturated fats from oxidation, it is best to keep them cool and in oxygen free environments.

TOFI (thin-outside-fat-inside) is used to describe lean individuals with a disproportionate amount of fat (adipose tissue) stored in their abdomen. The figure to illustrate this shows two men, both 35 years old, with a BMI of 25 kg/m. Despite their similar size, the TOFI had 5.86 litres of internal fat, whilst the healthy control had only 1.65 litres.

Subjects defined as TOFI with body mass index (BMI) <25 kg/m have increased levels of many of the risk factors associated with the metabolic syndrome. This phenotype is a further refinement of “metabolically-obese normal-weight" (MONW).

Subjects defined as TOFI have been described as being at higher risk of developing insulin resistance and type II diabetes due to the fact that they have reduced physical activity/VOmax, reduced insulin sensitivity, higher abdominal adiposity, and a more atherogenic lipid profile. Another important characteristic observed in this cohort is elevated levels of liver fat. It is shown that overconsumption of fructose can lead to TOFI by inducing inflammation associated cortisol release.

In 2011, coronary atherosclerosis was one of the top ten most expensive conditions seen during inpatient hospitalizations in the U.S., with aggregate inpatient hospital costs of $10.4 billion.

This is difficult to establish in the general population since the necessary imaging examinations are time consuming and expensive; however, in a recent research study it was estimated that 14% of the men and 12% of the women scanned with a BMI 20–25 kg/m were classified as TOFI.

Dunnigan-type familial partial lipodystrophy, also known as FPLD Type II and abbreviated as (FPLD2), is a rare monogenic form of insulin resistance characterized by loss of subcutaneous fat from the extremities, trunk, and gluteal region. FPLD recapitulates the main metabolic attributes of the insulin resistance syndrome, including central obesity, hyperinsulinemia, glucose intolerance and diabetes usually type 2, dyslipidemia, hypertension, and early endpoints of atherosclerosis. It can also result in hepatic steatosis. FPLD results from mutations in LMNA gene, which is the gene that encodes nuclear lamins A and C.

Native American men have a high prevalence of non-alcoholic fatty liver disease. Two genetic mutations for this susceptibility have been identified, and these mutations provided clues to the mechanism of NASH and related diseases.

Polymorphisms (genetic variations) in the single-nucleotide polymorphisms (SNPs) T455C and C482T in APOC3 are associated with fatty liver disease, insulin resistance, and possibly hypertriglyceridemia. 95 healthy Asian Indian men and 163 healthy non-Asian Indian men around New Haven, Connecticut were genotyped for polymorphisms in those SNPs. 20% homogeneous wild both loci. Carriers of T-455C, C-482T, or both (not additive) had a 30% increase in fasting plasma apolipoprotein C3, 60% increase in fasting plasma triglyceride and retinal fatty acid ester, and 46% reduction in plasma triglyceride clearance. Prevalence of non-alcoholic fatty liver disease was 38% in carriers, 0% wild (normal). Subjects with fatty liver disease had marked insulin resistance.

The percentage of people with non-alcoholic fatty liver disease ranges from 9 to 36.9% in different parts of the world. Approximately 20% of the United States population have non-alcoholic fatty liver, and the number of people affected is increasing. This means about 75 to 100 million people in the United States are affected.

The rates of non-alcoholic fatty liver disease is higher in Hispanics, which can be attributed to high rates of obesity and type 2 diabetes in Hispanic populations. Non-alcoholic fatty liver disease is also more common among men than women in all age groups until age 60, where the prevalence between sex equalize. This is due to the protective nature of estrogen. Fatty liver and NASH occur all ages, with the highest rates in the 40- to 49-year-old age group. It is the most common liver abnormality in children ages 2 to 19.